Groan!
Another in our occasional series of deplorable junction box botchery!
The sad thing is that this is an old Jaybeam aerial, and Jaybeam
(before they left the UK domestic aerial market having foolishly
tried to sell top quality products) included a balun in all their
aerials. A balun makes sure that the signal transfer from the
aerial to the cable is highly efficient and properly matched.
Then some dork comes along and shoves two cables into the box.
Oh dear.

Thanks to David Bolton of Ickenham Aerials (01895 622061 and 07909
898 591) for this photograph.